Mussel adhesive proteins (MAPs) are remarkable underwater adhesive materials secreted by certain marine organisms which form tenacious bonds to the substrates upon which they reside. During the process of attachment to a substrate, MAPs are secreted as adhesive fluid precursors that undergo a crosslinking or hardening reaction which leads to the formation of a solid adhesive plaque. One of the unique features of MAPs is the presence of L-3-4-dihydroxyphenylalanine (DOPA), an unusual amino acid which is believed to be responsible for adhesion to substrates through several mechanisms that are not yet fully understood. The observation that mussels adhere to a variety of surfaces in nature (metal, metal oxide, polymer) led to a hypothesis that DOPA-containing peptides can be employed as the key components of synthetic medical adhesives or coatings.
For example, bacterial attachment and biofilm formation are serious problems associated with the use of urinary stents and catheters as they often lead to chronic infections that cannot be resolved without removing the device. Although numerous strategies have been employed to prevent these events including the alteration of device surface properties, the application of anti-attachment and antibacterial coatings, host dietary and urinary modification, and the use of therapeutic antibiotics, no one approach has yet proved completely effective. This is largely due to three important factors, namely various bacterial attachment and antimicrobial resistance strategies, surface masking by host urinary and bacterial constituents, and biofilm formation. While the urinary tract has multiple anti-infective strategies for dealing with invading microorganisms, the presence of a foreign stent or catheter provides a novel, non-host surface to which they can attach and form a biofilm. This is supported by studies highlighting the ability of normally non-uropathogenic microorganisms to readily cause device-associated urinary tract infections. Ultimately, for a device to be clinically successful it must not only resist bacterial attachment but that of urinary constituents as well. Such a device would better allow the host immune system to respond to invading organisms and eradicate them from the urinary tract.
For example, bacterial attachment and subsequent infection and encrustation of uropathogenic E. coli (UPEC) cystitis is a serious condition associated with biofouling. Infections with E. coli comprise over half of all urinary tract device-associated infections, making it the most prevalent pathogen in such episodes.
Additionally, in the medical arena, few adhesives exist which provide both robust adhesion in a wet environment and suitable mechanical properties to be used as a tissue adhesive or sealant. For example, fibrin-based tissue sealants (e.g. Tisseel VH, Baxter Healthcare) provide a good mechanical match for natural tissue, but possess poor tissue-adhesion characteristics. Conversely, cyanoacrylate adhesives (e.g. Dermabond, ETHICON, Inc.) produce strong adhesive bonds with surfaces, but tend to be stiff and brittle in regard to mechanical properties and tend to release formaldehyde as they degrade.
Therefore, a need exists for materials that overcome one or more of the current disadvantages.